How Big Does a Semi Dwarf Tree Get?

It's All Relative

• When it comes to size designations, the principle of relativity rules. To understand the ultimate size of your semidwarf, you first need to know the natural, standard size of that same type of tree. Especially when working with fruit trees, semidwarf sizes reflect a percentage of the tree's standard size. A full-size apple tree, for example, hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9, grows to be 20 to 30 feet tall. A semidwarf apple might reach 40 percent to 60 percent of that size, or 12 to 18 feet.

Sizing Up Fruit Trees

• Different types of fruit trees vary significantly in their standard size. Their semidwarf sizes follow suit. While apple trees grow quite tall, other fruits typically mature at just 15 to 20 feet. Semidwarf trees of those fruit types will be proportionately shorter than semidwarf apples. Rootstocks affect fruit tree growth in other ways, too. Semidwarf trees are easier to cultivate and harvest. They also tend to fruit more heavily and bear fruit at an earlier age than standard trees. In general, a tree's spread will be equal to its height.

Fruit Rootstocks and Size

• With fruits, naturally small trees are rare. Semidwarf tree sizes are caused by what's called a semidwarfing rootstock. Most commercially grown fruit trees are actually two different trees united together in a process known as grafting. When you look at the trunk of the tree, you'll see the graft union where the trees were joined. The top part, called the scion, determines the variety of your fruit. The scion is the same whether grown as a standard, semidwarf or dwarf. The bottom part, called the rootstock, determines how fast and how large your semidwarf tree will grow.

Sizes in Other Tree Types

• When shopping for trees other than fruits, the same principle of relativity applies. Semidwarf trees, however, are usually naturally occurring. Selected because of their natural genetic size, they stay on their own roots. No dwarfing rootstock is involved. Designations are much more subjective. Labels such as semidwarf, dwarf, pygmy and others abound -- all relative to one another and whatever plant is involved. Current research in the forestry industry brings another factor into play. In hope of capturing advantages seen with fruits, scientists are experimenting with genetic modification to create semidwarf sizes in other types of trees.